1. Field of the Invention:
This invention relates to earth boring bits--especially to methods of improved manufacture.
2. Description of the Prior Art:
The typical earth boring (rock) bit used in the drilling of oil, gas or other mineral wells employs a body composed of several--usually three--lugs. A cantilevered bearing shaft depends from each lug to support a rotatable cutter with earth disintegrating teeth. Each lug has machined faces that mate with similar, opposed faces on the adjacent lugs and, when welded, a fluid tight body results.
The lugs of a rock bit must be manufactured and welded accurately to achieve a geometry that conforms with design criteria. It has been especially difficult to establish the requisite accuracy in the machining of the opposed faces of the lugs. These faces, called 120 degree faces on a three cone bit, must be accurate if the bit which results is to achieve an economical use in the harsh environment encountered during drilling.